Institute of Cancer of Sao Paulo State, School of Medicine, University of Sao Paulo, Sao Paulo 01246903, Brazil.Departments of Pathology and Neurology, School of Medicine, University of Sao Paulo, Sao Paulo 01246903, Brazil.

New Adventures of Old Pap Smear

Patients generally do not enjoy getting a Pap smear, but the procedure has saved hundreds of thousands of lives in the decades since its inception. The now-routine smear, which allows doctors to detect abnormal cells in a woman’s cervix before they turn into an invasive cancer, was updated a decade ago to screen for DNA from human papillomavirus, the pathogen known to cause cervical cancer. Now, Kinde and coauthors have developed a technique that may make the Pap smear even more versatile by expanding it into a test for multiple cancers, including endometrial and the dreaded ovarian cancer, which is essentially untreatable unless it is caught early.

The authors first assembled a catalog of common mutations in these cancers, drawing on previously published data for ovarian cancer and new data on 22 endometrial tumors. They tested 46 samples from patients with endometrial or ovarian cancers and confirmed that all 46 harbored at least some of the common genetic changes on their list. Kinde et al. then hypothesized that ovarian and endometrial cancers likely shed cells from their surfaces and that such cells may be detectable among the cervical cells in a Pap smear, if one knew how to identify them. Thus, the authors used massively parallel sequencing to test patients’ Pap specimens for some of the more common mutations found in the cancer cells. In the initial set of samples, 100% of endometrial cancers and 41% of ovarian cancers were detectable by this method.

This new approach to Pap testing is not yet ready for clinical use and will not serve as a foolproof method of diagnosing genital tract tumors, particularly ovarian cancer. More research is needed to validate the current results in larger groups of patients and to improve the yield of screening for ovarian tumors, perhaps by modifying the technique doctors use to collect sample cells for the Pap test. Importantly, though, the new test has not misclassified any healthy woman as harboring a cancer, raising the possibility of its eventual use as a screening test for cancer. Even if this approach cannot identify every ovarian tumor, it may be able to detect more of them earlier and more accurately than is possible with existing methods. Once the findings of Kinde et al. are fully validated and the new test gains approval, women will have even more reasons to make sure they get their Pap smears routinely.